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Akt inhibitors as an HIV-1 infected macrophage-specific anti-viral therapy.

Chugh P, Bradel-Tretheway B, Monteiro-Filho CM, Planelles V, Maggirwar SB, Dewhurst S, Kim B - Retrovirology (2008)

Bottom Line: Interestingly, the expression of HIV-1 or SIV Tat is sufficient to mediate this cytoprotective effect, which is dependent on the basic domain of Tat - a region that has previously been shown to bind p53.Next, we observed that this interaction appears to contribute to the downregulation of PTEN expression, since HIV-1 Tat was found to compete with PTEN for p53 binding; this is known to result in p53 destabilization, with a consequent reduction in PTEN protein production.Since HIV-1 infected macrophages display highly elevated Akt activity, our results collectively show that PI3K/Akt inhibitors may be a novel therapy for interfering with the establishment of long-living HIV-1 infected reservoirs.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Microbiology and Immunology, School of Medicine, University of Rochester Medical Center 601 Elmwood Avenue Box 672 Rochester, New York 14742 USA. Pauline_Chugh@urmc.rochester.edu

ABSTRACT

Background: Unlike CD4+ T cells, HIV-1 infected macrophages exhibit extended life span even upon stress, consistent with their in vivo role as long-lived HIV-1 reservoirs.

Results: Here, we demonstrate that PI3K/Akt inhibitors, including clinically available Miltefosine, dramatically reduced HIV-1 production from long-living virus-infected macrophages. These PI3K/Akt inhibitors hyper-sensitize infected macrophages to extracellular stresses that they are normally exposed to, and eventually lead to cell death of infected macrophages without harming uninfected cells. Based on the data from these Akt inhibitors, we were able to further investigate how HIV-1 infection utilizes the PI3K/Akt pathway to establish the cytoprotective effect of HIV-1 infection, which extends the lifespan of infected macrophages, a key viral reservoir. First, we found that HIV-1 infection activates the well characterized pro-survival PI3K/Akt pathway in primary human macrophages, as reflected by decreased PTEN protein expression and increased Akt kinase activity. Interestingly, the expression of HIV-1 or SIV Tat is sufficient to mediate this cytoprotective effect, which is dependent on the basic domain of Tat - a region that has previously been shown to bind p53. Next, we observed that this interaction appears to contribute to the downregulation of PTEN expression, since HIV-1 Tat was found to compete with PTEN for p53 binding; this is known to result in p53 destabilization, with a consequent reduction in PTEN protein production.

Conclusion: Since HIV-1 infected macrophages display highly elevated Akt activity, our results collectively show that PI3K/Akt inhibitors may be a novel therapy for interfering with the establishment of long-living HIV-1 infected reservoirs.

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Related in: MedlinePlus

SIV Tat also exerts a cytoprotective effect. (A) Sequence comparison of the cysteine-rich and basic domains from HIV-1 YU-2, SIV mac239 and SIV PBJ. Numbers indicate residues on the first amino acids of the shown sequences. Colored residues in HIV-1 Tat were mutated in this study. (B) CHME5 cells were cotransfected with a plasmid encoding GFP and constructs expressing the first exon of HIV-1 Tat (psvTat72), SIV-PBJ Tat, or with an empty plasmid (pcDNA3.1) using Lipofectamine. Cells were then treated with LPS/CHX and analyzed for cell death. Bright fields (BF) and merged (red+green) fields are shown. Transfected cells are GFP+ cells (green), dead cells (red). The percentage of cell death induced in GFP+, EthD+ cells is shown with the SD from three independent experiments.
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Figure 6: SIV Tat also exerts a cytoprotective effect. (A) Sequence comparison of the cysteine-rich and basic domains from HIV-1 YU-2, SIV mac239 and SIV PBJ. Numbers indicate residues on the first amino acids of the shown sequences. Colored residues in HIV-1 Tat were mutated in this study. (B) CHME5 cells were cotransfected with a plasmid encoding GFP and constructs expressing the first exon of HIV-1 Tat (psvTat72), SIV-PBJ Tat, or with an empty plasmid (pcDNA3.1) using Lipofectamine. Cells were then treated with LPS/CHX and analyzed for cell death. Bright fields (BF) and merged (red+green) fields are shown. Transfected cells are GFP+ cells (green), dead cells (red). The percentage of cell death induced in GFP+, EthD+ cells is shown with the SD from three independent experiments.

Mentions: Next, we attempted to identify the domain(s) of Tat protein that is/are responsible for the cytoprotective effect. Here, two highly conserved functional domains of Tat protein were investigated: the cysteine rich domain, a domain required for the transactivation activity of HIV-1 Tat [36,37], and the basic domain, which is involved in the cellular uptake, nuclear localization, and transcriptional transactivator functions of Tat [36,38-40] (see Figure 6A for amino acid sequences).


Akt inhibitors as an HIV-1 infected macrophage-specific anti-viral therapy.

Chugh P, Bradel-Tretheway B, Monteiro-Filho CM, Planelles V, Maggirwar SB, Dewhurst S, Kim B - Retrovirology (2008)

SIV Tat also exerts a cytoprotective effect. (A) Sequence comparison of the cysteine-rich and basic domains from HIV-1 YU-2, SIV mac239 and SIV PBJ. Numbers indicate residues on the first amino acids of the shown sequences. Colored residues in HIV-1 Tat were mutated in this study. (B) CHME5 cells were cotransfected with a plasmid encoding GFP and constructs expressing the first exon of HIV-1 Tat (psvTat72), SIV-PBJ Tat, or with an empty plasmid (pcDNA3.1) using Lipofectamine. Cells were then treated with LPS/CHX and analyzed for cell death. Bright fields (BF) and merged (red+green) fields are shown. Transfected cells are GFP+ cells (green), dead cells (red). The percentage of cell death induced in GFP+, EthD+ cells is shown with the SD from three independent experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2265748&req=5

Figure 6: SIV Tat also exerts a cytoprotective effect. (A) Sequence comparison of the cysteine-rich and basic domains from HIV-1 YU-2, SIV mac239 and SIV PBJ. Numbers indicate residues on the first amino acids of the shown sequences. Colored residues in HIV-1 Tat were mutated in this study. (B) CHME5 cells were cotransfected with a plasmid encoding GFP and constructs expressing the first exon of HIV-1 Tat (psvTat72), SIV-PBJ Tat, or with an empty plasmid (pcDNA3.1) using Lipofectamine. Cells were then treated with LPS/CHX and analyzed for cell death. Bright fields (BF) and merged (red+green) fields are shown. Transfected cells are GFP+ cells (green), dead cells (red). The percentage of cell death induced in GFP+, EthD+ cells is shown with the SD from three independent experiments.
Mentions: Next, we attempted to identify the domain(s) of Tat protein that is/are responsible for the cytoprotective effect. Here, two highly conserved functional domains of Tat protein were investigated: the cysteine rich domain, a domain required for the transactivation activity of HIV-1 Tat [36,37], and the basic domain, which is involved in the cellular uptake, nuclear localization, and transcriptional transactivator functions of Tat [36,38-40] (see Figure 6A for amino acid sequences).

Bottom Line: Interestingly, the expression of HIV-1 or SIV Tat is sufficient to mediate this cytoprotective effect, which is dependent on the basic domain of Tat - a region that has previously been shown to bind p53.Next, we observed that this interaction appears to contribute to the downregulation of PTEN expression, since HIV-1 Tat was found to compete with PTEN for p53 binding; this is known to result in p53 destabilization, with a consequent reduction in PTEN protein production.Since HIV-1 infected macrophages display highly elevated Akt activity, our results collectively show that PI3K/Akt inhibitors may be a novel therapy for interfering with the establishment of long-living HIV-1 infected reservoirs.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Microbiology and Immunology, School of Medicine, University of Rochester Medical Center 601 Elmwood Avenue Box 672 Rochester, New York 14742 USA. Pauline_Chugh@urmc.rochester.edu

ABSTRACT

Background: Unlike CD4+ T cells, HIV-1 infected macrophages exhibit extended life span even upon stress, consistent with their in vivo role as long-lived HIV-1 reservoirs.

Results: Here, we demonstrate that PI3K/Akt inhibitors, including clinically available Miltefosine, dramatically reduced HIV-1 production from long-living virus-infected macrophages. These PI3K/Akt inhibitors hyper-sensitize infected macrophages to extracellular stresses that they are normally exposed to, and eventually lead to cell death of infected macrophages without harming uninfected cells. Based on the data from these Akt inhibitors, we were able to further investigate how HIV-1 infection utilizes the PI3K/Akt pathway to establish the cytoprotective effect of HIV-1 infection, which extends the lifespan of infected macrophages, a key viral reservoir. First, we found that HIV-1 infection activates the well characterized pro-survival PI3K/Akt pathway in primary human macrophages, as reflected by decreased PTEN protein expression and increased Akt kinase activity. Interestingly, the expression of HIV-1 or SIV Tat is sufficient to mediate this cytoprotective effect, which is dependent on the basic domain of Tat - a region that has previously been shown to bind p53. Next, we observed that this interaction appears to contribute to the downregulation of PTEN expression, since HIV-1 Tat was found to compete with PTEN for p53 binding; this is known to result in p53 destabilization, with a consequent reduction in PTEN protein production.

Conclusion: Since HIV-1 infected macrophages display highly elevated Akt activity, our results collectively show that PI3K/Akt inhibitors may be a novel therapy for interfering with the establishment of long-living HIV-1 infected reservoirs.

Show MeSH
Related in: MedlinePlus